Preload is a force acting between the rolling elements and bearing rings that is not caused by an external load. Preload can be regarded as negative internal clearance. Reasons to apply preload include:
- enhanced stiffness
- reduced noise level
- improved shaft guidance
- extended bearing service life
- improved running accuracy
- prevent skidding in high-speed applications during rapid starts and stops and under very light or no-load conditions
In the majority of high-precision applications preload is needed to enhance system rigidity.